SRC/sgecon.f(3)

NAME
SRC/sgecon.f

SYNOPSIS

  Functions/Subroutines
subroutine sgecon (norm, n, a, lda, anorm, rcond, work, iwork, info)
SGECON

Function/Subroutine Documentation

  subroutine sgecon (character norm, integer n, real, dimension( lda, * ) a, integer lda, real anorm, real rcond, real, dimension( * ) work, integer, dimension( * ) iwork, integer info)

SGECON

Purpose:

    !>
    !> SGECON estimates the reciprocal of the condition number of a general
    !> real matrix A, in either the 1-norm or the infinity-norm, using
    !> the LU factorization computed by SGETRF.
    !>
    !> An estimate is obtained for norm(inv(A)), and the reciprocal of the
    !> condition number is computed as
    !>    RCOND = 1 / ( norm(A) * norm(inv(A)) ).
    !>

Parameters
    NORM

    !>          NORM is CHARACTER*1
    !>          Specifies whether the 1-norm condition number or the
    !>          infinity-norm condition number is required:
    !>          = '1' or 'O':  1-norm;
    !>          = 'I':         Infinity-norm.
    !>

    N

    !>          N is INTEGER
    !>          The order of the matrix A.  N >= 0.
    !>

    A

    !>          A is REAL array, dimension (LDA,N)
    !>          The factors L and U from the factorization A = P*L*U
    !>          as computed by SGETRF.
    !>

    LDA

    !>          LDA is INTEGER
    !>          The leading dimension of the array A.  LDA >= max(1,N).
    !>

    ANORM

    !>          ANORM is REAL
    !>          If NORM = '1' or 'O', the 1-norm of the original matrix A.
    !>          If NORM = 'I', the infinity-norm of the original matrix A.
    !>

    RCOND

    !>          RCOND is REAL
    !>          The reciprocal of the condition number of the matrix A,
    !>          computed as RCOND = 1/(norm(A) * norm(inv(A))).
    !>

    WORK

    !>          WORK is REAL array, dimension (4*N)
    !>

    IWORK

    !>          IWORK is INTEGER array, dimension (N)
    !>

    INFO

    !>          INFO is INTEGER
    !>          = 0:  successful exit
    !>          < 0:  if INFO = -i, the i-th argument had an illegal value.
    !>                NaNs are illegal values for ANORM, and they propagate to
    !>                the output parameter RCOND.
    !>                Infinity is illegal for ANORM, and it propagates to the output
    !>                parameter RCOND as 0.
    !>          = 1:  if RCOND = NaN, or
    !>                   RCOND = Inf, or
    !>                   the computed norm of the inverse of A is 0.
    !>                In the latter, RCOND = 0 is returned.
    !>

Author
    Univ. of Tennessee

    Univ. of California Berkeley

    Univ. of Colorado Denver

    NAG Ltd.

Definition at line 130 of file sgecon.f.

Author

Generated automatically by Doxygen for LAPACK from the source code.